This invention relates to an internal combustion engine with fuel injection, and in particular, to an adjustable high volume exhaust valve for two-cycle engines. The adjustable high volume valve is particularly suitable for high speed short stroke engines in which fuel economy is maximized over a wide range of operating conditions.
The technology of engine design is currently focusing on air flow into and out of the cylinders as a primary avenue for maximizing power at the same time as minimizing fuel consumption. It has been discovered however, that certain air flow designs that maximize air flow into and out of the cylinders under peak performance conditions, fail to function properly under low speed conditions. For example, in certain advanced four and five valve, four-cycle, aspirated engines insufficient turbulence is generated to insure complete combustion during low operating speeds. In two-cycle engines, maximizing intake and exhaust conditions for peak performance will result in overscavenging at low speed conditions, resulting in not only a loss of fuel in spark ignited engines, but a waste of the charge and cooling of the exhaust flow in turbo-charged, autocombustion engines.
Furthermore, where adiabatic conditions are attempted to be maintained in the combustion chamber for autocombustion of injected fuel, an overscavenging can result in a substantial temperature loss to the combustion chamber resulting in incomplete or a total failure of combustion at low operating conditions.
In adapting the two-cycle diesel engine to automotive applications, the performance must match the current fuel efficient, high performance gasoline engines. While low rpm, long-stroke diesel work engines are particularly effective for a high load, constant speed, operating situation, rapid response at various speeds is conventionally lacking in such engines. The common two-stroke, high rpm, recreational engines having both intake and exhaust ports located in the cylinder wall exposed by the piston at the end of its power stroke, are unsuitable for automotive use because of antipollution requirements.
Advanced designs using multiple valves in the cylinder head with intake ports in the cylinder walls are comparatively effective in minimizing pollution and maximizing air flow. However, the total area even in four valve exhaust systems, approximates only 25% of the bore area of the cylinder. Furthermore, such multiple valve cylinder heads are not only enormously complex, high in cost, and low in reliability, but structurally form a weak head configuration that is limited in its capacity to support the high pressures and temperatures that make diesel or other autocombustion engines particularly desirable for maximum fuel efficiency.
Because most high performance engines must be designed for the variable operating conditions of the modern automobile for broad commercial success, the results are compromised designs which are neither optimized for high speed nor low speed conditions. The object of this invention is therefore to devise a design configuration for an internal combustion, fuel injected engine that has a variable air flow system that can be optimized for any operating conditions, and thus deliver an economical peak performance throughout the various speed and load conditions normally encountered by the modern, high-performance vehicle.